One vertex per element, one color per generator, with an edge from x to x·s.
(2,6)(3,8)(9,10,13,11)(12,14,16,15)(17,18)(19,23)(20,24)(21,22)(26,30)(28,35)(31,36)(34,39)(1,2)(3,4)(5,6)(7,8)(10,11)(14,15)(18,22)(20,23)(26,30)(27,33)(32,37)(34,39) involution — undirected(2,6)(4,7)(9,10,13,11)(12,15,16,14)(17,19,21,24)(18,23,22,20)(25,26,29,30)(27,31,33,36)(28,32,35,37)(34,38,39,40)(1,3,5,8)(2,7,6,4)(9,11,13,10)(12,14,16,15)(17,20)(18,19)(21,23)(22,24)(25,27)(26,31)(28,34)(29,33)(30,36)(32,38)(35,39)(37,40)(1,4,5,7)(2,3,6,8)(9,12)(10,14)(11,15)(13,16)(17,19)(18,23)(20,22)(21,24)(25,28)(26,32)(27,34)(29,35)(30,37)(31,38)(33,39)(36,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.